The majority of all laminate floors are produced according to a production method generally referred to as Direct Pressed Laminated (DPL). Such laminated floors comprise a core of a 6-12 mm fibre board, a 0.2 mm thick upper decorative surface layer of laminate and a 0.1-0.2 mm thick lower balancing layer of laminate, plastic, paper or like material.
The surface layer of a laminate floor is characterized in that the decorative and wear properties are generally obtained with two separate layers of paper, one above the other. The decorative layer is generally a printed paper and the wear layer is a transparent overlay paper, which comprises small aluminium oxide particles.
The printed decorative paper and the overlay are impregnated with melamine formaldehyde resins and laminated to a HDF core in large laminate presses where the resin cures under high heat (160-200 degrees Celsius) and pressure and the papers are laminated to the core material. An embossed press plate forms the surface structure. Sometimes a structured paper is used as a press matrix.
Laminated floors may also be produced with printing technology. One advantage is that the pressing operation may be avoided and that no printed papers are needed to provide a decorative wear resistance surface.
Floor panels with a Direct Printed Laminate surface comprise the same type of HDF core as DPL. The décor is printed directly onto the core. The production process is rather complicated and is only cost efficient in very large production volumes.
Hydro printing inks are used to print the décor by a multicolour printing press with rollers that print directly onto the pre-sealed core. The printed décor layer must be protected against wear. The most common method to achieve high abrasive strength is to use, anti-abrasive UV sealers, which are applied on the print by rollers and cured by UV light. Embossed structures may be formed by embossed rollers.
Direct printing technology may be replaced with Digital printing Technology that is much more flexible and small production volumes can be economically manufactured. The difference between these two methods is mainly the printing step where printing rollers are replaced by a digital non-contact printing process and where the desired image is directly applied on to the pre-finished core. The final transparent coating which protects the digital image and the structured surfaces are usually of the same type as used in direct printing. Any types or printed images may be created but the surface structure is always limited to the form of the embossed rollers or structured films that are pressed against the surface.
Digital printing may also be used to print on a paper sheet that is used in conventional laminate production. The print may be applied on a separate impregnated or non-impregnated paper that after printing is applied on a core. A raw paper may also be applied on a core comprising a resin that, during pressing, penetrates into the raw paper. The main advantage is that impregnation and very accurate positioning of the paper may be avoided.
Recently new “paper free” floor types have been developed with solid surfaces comprising a substantially homogenous powder mix of fibres, binders and wear resistant particles.
The powder mix may comprise aluminium oxide particles, melamine formaldehyde resins and wood fibres. In most applications decorative particles such as, for example colour pigments are included in the mix. In general all these materials are applied in dry form as a mixed powder on a HDF core and cured under heat and pressure to a 0.1-1.0 mm solid layer. Melamine formaldehyde resin and wood fibres may be replaced by thermoplastic particles.
Several advantages over known technology and especially over conventional laminate floorings may be obtained such as increased wear and impact resistance, deep embossing, increased production flexibility and lower costs.
Powder technology is very suitable to produce a decorative surface layer, which is a copy of stone and ceramics. It is however more difficult to create designs such as, for example wood decors. However, recently digital powder printing has been developed and it is possible to create very advanced designs of any type by injecting a digital print into the powder prior to pressing. The surface structure is made in the same way as for laminate flooring by a structured press plate or an embossed matrix paper that is pressed against the powder.
Floors with a surface of wood are produced in many different ways. Traditional solid wood floors have developed into engineered floors with wood layers applied on a core made of wood lamellas, HDF or plywood. The majority of such floors are delivered as pre-finished floors with a wood surface that is coated with several transparent layers in the factory. Recently wood floorings have also been produced with a digitally printed pattern that improves the design of the wood grain structure in wood species that do not have a sufficient surface quality.
The majority of all the above-described floors have an embossed surface structure, especially when the decorative printed décor is a wood pattern. The embossed structure was in the past provided as a separate general structure type that was used for many different décor types. Recently most floor producers have introduced the so-called Embossed In Register (EIR) method where the embossed surface structure is specifically formed for each type of wood species and the embossing is made in register with the printed décor. This provides advanced designs that are difficult to differentiate from the natural materials such as wood and stone. Embossed surfaces are an essential part of the surface structure and design and it would be an advantage if such structures may be formed in a more flexible and cost efficient way.